Basically the wheel is spun by an electric motor, so the piston/bolt lets a BB in then smacks it out and keeps repeating while the motor spins. The only flaw I can think of is that the motor will be too fast and end up making it so that the BBs don't have enough time to fall in front of the piston.

I might use a spring powered piston fed mag design and I might put holes in the magazine or somewhere because no air is used.
(rpm/60)(diameter/12)=fps according to you, so I'll play with the equation. And this will be for airsoft, so I don't want too high of speeds. I want to be able to use it in wars against my friends.